Muffler with insulated internal sound dispersing and absorbing chambers

ABSTRACT

A muffler for internal combustion engines is provided with a plurality of series aligned sound and heat attenuating units with each unit having a sound absorbing perforated chamber interconnected by a perforated conduit containing a spiral-formed baffle for sound wave and heat deflection. The spiral-formed baffles increase the length of the exhaust gas flow path through the conduit and break up the heat and sound wave patterns as said baffles deflect the heat and sound waves through perforations into the surrounding chamber. Part of the deflected sound waves and heat of the gases in the chamber pass through the perforations in the chamber walls into heat and sound insulation or attenuation material with the remaining deflected sound waves and heat passing on into the next in the series of spiral baffled conduit and chamber units until the sound waves and heat in the gases are dissipated to an acceptable level for discharge of the gases from the muffler.

Matted States Patent [191 Getz et a1.

1 1 MUFFLER WITH INSULATED INTERNAL SOUND DISPERSING AND ABSORBING CHAMBERS [75] Inventors: Marvin G. Getz, Morton; Gerald E. Whitehurst, East Peoria; Gerald M. Walden, Chillicothe. all of 111.

[73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: Apr. 19, 1974 21 Appl. No.: 462,450

Primary E.taminerRichard B. Wilkinson Assistant ExaminerJohn F. Gonzales Attorney, Agent, or Firm-Wegner, Stellman, McCord, Wiles & Wood Dec. 3, 1974 57 ABSTRACT A muffler for internal combustion engines is provided perforated chamber interconnected by a perforated conduit containing a spiral-formed baffle for sound wave and heat deflection. The spiral-formed baffles increase the length of the exhaust gas flow path through the conduit and break up the heat and sound wave patterns as said baffles deflect the heat and sound waves through perforations into the surrounding chamber. Part of the deflected sound waves and heat of the gases in the chamber pass through the perforations in the chamber walls into heat and sound insulation or attenuation material with the remaining d6 fiected sound waves and heat passing on into the next in the series of spiral baffled conduit and chamber units until the sound waves and heat in the gases are dissipated to an acceptable level for discharge of the gases from the muffler.

12 Claims, 3 Drawing Figures MUFFLER WITH-I INSULATED INTERNAL SOUND DISPERSING AND ABSORBING CHAMBERS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to mufflers for internal combustion engine and, more particularly, to mufflers having at least two series oriented sound and heat absorbing members for successively reducing the amount and the extent of the objectionable elements.

2. Description of the Prior Art lntemal combustion engines inherently produce large volumes of exhaust gases which are expelled from the engine with loud explosions and contain considerable heat and pollutants. The larger the engine, the larger the amount of exhaust and the larger is the problem of control of the undesirable characteristics of said exhaust. Current governmental regulations require' maintaining exhaust emission noise levels below a preset value. In many instances, the only way to meet the standards set by the regulations is to use primary and secondary mufflers which result in increased expense and increased space requirements. v

In very large engines, such as large crawler-type tractors, the amount of space required to mount currently available mufflers of adaquate capacity is so great that severe space problems have resulted. In addition, current mufflers when mounted in the only available places in the engine compartment cause failures of heat susceptible members such as coatings on wires and fluid hoses due to the large amount of heat radiated by said mufflers.

Most current mufflers are either of the straight through, baffled arrangement or of the reversed flow, baffled arrangement which mufflers fail to provide sufficient retarding, damping or absorption of heat and sound energy to meet gov'emmental regulations.

SUMMARY OF THE INVENTION The invention provides for a muffler with a closed container or housing having ingress and egress openings therein. The ingress opening has a conduit therein extending into a chamber which conduit and chamber combined, form one unit of several units which are connected in a series of at least two units with the last of the series having an outlet for egress of the exhaust from the muffler.

Each conduit and chamber unit is mounted in the housing and is surroundedby sound and heat attenuation or insulation material. The conduit and chamber units within the housing having a plurality of perforations or apertures through the walls thereof and opening into the attenuation or insulation material in the housing. Spiral baffles are mounted in each conduit for diverting, deflecting and lengthening the flow path of the sound waves and heat of the exhaust gases to disperse said sound waves and heat into the chamber surrounding the conduit. The sound waves and heat of the exhaust gases in the chamber are deflected or diverted either through the perforations or apertures in the walls and ends of the chamber and into the sound and heat attenuation or insulation material or through the conduit of the next in the series conduit and chamber units. Both the deflections and diversions of the sound waves and heat of the gases into the units and into the attenuation or insulation material serve to absorb and dissipate the sound waves, the heat and the velocity of the exhaust gases so that the gases emitted from the outlet of the muffler will be well within the allowable governmental regulations.

BRIEF DESCRIPTION OF THE DRAWINGS The details of construction and operation of the invention are more fully described with reference to the accompanying drawings which form a part hereof and in which like reference numerals refer to like parts throughout.

In the drawings:

FIG. 1 is a broken away sectional plan view of the muffler showing our invention;

FIG. 2 is a cross-sectional view taken along the lines 22 of FIG. 1; and,

FIG. 3 is an enlarged sectional view of a portion of a conduit showing details of the spiral-formed baffle and the apertures therein.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a mufller 10 is shown and includes a closed housing 11 of generally rectangular shape with four side walls 12, a bottom wall 13 and a, top wall 14. The four side walls 12 and the bottom wall 13 are shown formed of one piece of sheet metal although they could be several separate pieces welded or otherwise joined together. The top walll4 is provided with downtumed side edges 15 which are adapted to overlap the outside surfaces of the four side walls 12 when it is fastened in position. The top wall 14 is adapted to be welded to the rest of the housing for use although other fastening means are contemplated. The housing 11 is made of heavy gauge, rust and heat resistant material and under certain sets of circumstances, it is contemplated that the top wall 14 may be removed by breaking the welds for inspection and servicing of the parts and components therein. In most circumstances, it is recognized that because of the high temperatures involved and the corrosive nature of the exhaust gases passing therethrough, that the housing 11 and the operative parts of the mufiler will deteriorate and, therefore, the whole muffler will be discarded and replaced.

The housing 11 is adapted to enclose a plurality of inlet conduits l6 and chambers 18 which conduits and chambers are connected in series and are embeddedin sound and heat attenuation or insulation material. For the purposes of our invention, each chamber 18 and its associated inlet conduit 16 is entitled a unit and it is contemplated that at least two units 20, 20A will be mounted in series in the housing 11.

The first unit 20 of the series of units has the inlet conduit 16 extending through and fastened to the one side wall 12 of the housing 11 and through an inlet end wall 22 of the chamber 18. The inner end portion 24 of the conduit 16 is secured in said chamber 18 by means of a web or perforated baffle plate 26 carried by the wall 27 of said chamber. The wall of the conduit 16 is sealed to the wall 12 of the housing to prevent escape of gases around said conduit. The conduit 16 will have a plurality of apertures or perforations 28 around the outer periphery thereof from a point just inside the wall 12 of the housing down to the end cap or cover 30 of the conduit. The end cap or cover 30 of the conduit will have no perforations therein so as to force the exhaust gases out through the perforations 28 in the walls of the I 36A throughout.

conduit. Affixedly mounted within the conduit 16 is a spiral-shaped baffle 32 which is formed of sheet material and is adapted to have the edges thereof make contact with and be fastened to the inner surface of the wall 34 of the conduit.

The chamber 18, which in its illustrated form, is a I The space between each unit and between the units and somewhat elliptical-shaped cylinder in cross section (see FIG. 2) and has apertures or perforations 36 through the side wall 27 and inlet end wall 22 and outlet end wall 38 thereof. The outlet end wall 38 of the chamber 18, opposite the wall through which the inlet conduit 16 passes, has an opening 40 through which an inlet conduit 16A for a second unit 20A projects.

The conduit 16A is held in position in the chamber I 18 by means of a web or perforated baffle plate 42 secured to the inner surface of the wall 27 of the chamber. The inlet end of conduit 16A is shown misaligned with the closed end of conduit 16. It should be recognized that there is no functional significance to this misalignment. The inlet 16 can be located in any selected position that is most convenient for connection to the .the outlet end of the conduit 16A with no perforations formed therethrough.

The second unit 20A, in addition to the conduit 16A connected in the first unit, has a chamber 18A into which the conduit 16A passes. A web or baffle plate 46 is secured to the inner surface of the walls of the chamber 18A and to the end portion of the conduit 16A for supporting the conduit 16A in said chamber. The side end walls of the second chamber 18A have perforations A third unit 20B has an inlet conduit 16B and a the walls of the housing 11 is packed with sound and heat attenuating and insulating material. As has been discussed hereinabove, it is contemplated that at least two units be incorporated in the muffler which'units connected in series, aligned relationship. The output capacity of the engine, together with the requirements of the regulations on exhaust emissions, determines the number of series, aligned units .to be incorporated in the muffler.

In use, the inlet conduit 16 is connected'to the ex haust outlet of the vehicle so that exhaust gases will be propelled into the conduit 16 whereupon they will strike the spiral-shaped baffie 32 and be given a spiral motion for lengthening the flow path of the gases. The

exhaust enters the conduit 16 of the muffler with high energy sound waves and high temperature gases and due to the spiral baffle said sound wavesand gases are diffused and diverted toward and through said apertures or perforations 28. Some of the sound waves and gases pass through the perforations immediately while v others are deflected back along the baffle until eventu chamber 18B such: that the conduit 16B is supported by web or perforated baffle 50 in the second chamber 18A and in the third chamber 183 by web or perforated baffle 52. The conduit 16B has perforations 288 throughout its length and has an end cap or cover 56 which cover has no perforations therethrough. A spiralshaped baffle 32B is positioned in a portion or in all of the length of conduit 16B with the inlet end of the con- 'duit 16B in the second chamber 18A opened and facing into said chamber. The chamber 18B is perforated throughout and is similar in design and construction to chambers 18A and 18 and, as shown, is positioned between chambers 18 and 18A in series alignment with chamber 18A,by means of perforated'conduit 168. An outlet tube 58 connects the inside of the third chamber 18B through the top wall 14 of the muffler and is adapted to be connected with the exhaust pipe of the vehicle.

Surrounding the chambers 18, 18A, 18B and the exposed portions of the conduits 16, 16A, 16B within the housing 11 is sound and heat attenuation or insulation material 60 which has both heat and sound absorbing characteristics. The units 20, 20A and 203, which in the present illustrated form are three in number, are aligned in series and are nested relative to each other in the housing 11 so as to be'spaced from one another.

ally all of said sound waves and gases pass into the chamber 18. The exhaust gases will be propelled through the apertures-or perforations 28 in the walls of the conduit 16 into the chamber 18 wherein the sound waves and hot gases will bounce and reverberate in the chamber with some passing through the perforations 36 in the walls of the chamber 18 and into the sound and heat attenuating and insulating material. The attenuating and insulating material will absorb the sound waves and dissipate much of the heat from the gases. The remaining sound waves and hot gases in the'chamber 18 will pass through the apertures or perforations 28A in the walls of the inlet conduit 16A as well as through the open end of said conduit. The sound waves and hot gases will be propelled along the' spiral-shaped bafile 32A in the conduit 16A of the second, unit 20A with some of said sound waves and gases being propelled through the apertures or perforations 28A in the walls of .the second conduit 16A for diffusion and dispersion in the sound and heat attenuating or insulating material 60 surrounding the second conduit 16A as the conduit passes from the first unit 20 to the chamber 18A of the second unit 20A. The sound waves and hot. gases not diffused or dispersed into the insulating material 60 will pass through the perforations 28A in the walls of the inner portion of the second inlet conduit 16A and into the second chamber 18A where, once again, some of the sound waves and hot gases will pass through the perforations 36A in chamber 18A and into sound attenuating and heat insulating material 60, with the remaining passing through the perforations 28B and into the open end of the inlet conduit 16B of the third unit 208. The sound waves and hot gases in the conduit 16B will be deflected into a long spiral path'by the spiral of said conduit 16B and into the third chamber 20B.

There, once again, someof the sound waves and hot gases will pass through the perforations 368 in the walls exhaust gases passing out through the exit tube 58 into 5 the tail pipe of the engine and thence into the atmosphere.

In FIG. 1 of the drawings is illustrated perforated baffles 26 and 42 as supporting the conduits l6 and 16A in chamber 18 of the unit 20, with comparable perfo- 1 rated baffles 46, 50 supporting conduits 16A, MB in chamber 18A of unit 20A and with a perforated baffle 52 supporting conduit 168 in chamber 18B of unit 20B. In each chamber 18, 18A and 188 the effect of the baffies is to subdivide the respective chambers into sub- 1 chambers such that the exhaust gases are further diverted or deflected in passing from the inlet end portion of each chamber through the intermediate portion to the outlet end portion thereof. The baffles within each chamber further dissipate the undesirable characteristics of the exhaust gases as said gases pass through the perforations in the baffles or as said gases are further deflected back into the chamber by the material between the perforations in the baffles. Therefore, the bafiles 26,42 and 46,50 and 52 within the respective chambers 18, 18A and 18B further contribute to dispersing and reducing the undesirable characteristics such as sound waves and heat of the exhaust gases.

In some designs not requiring the maximum dispersion or deflection of the gases, the perforated baffles 26,42, 46,50 and 52 may be replaced by thin support webs without departing from the spirit of our invention.

with the exhaust gases passing through the perforations and conduits from one conduit and chamber unit to the next and with much of the sound waves, heat and velocity of the gases being absorbed and dissipated by the sound and heat attenuating and insulating material surrounding the chambers and the conduits, the exhaust gases by the time they reach the exit pipe are relatively quiet and cool and when the muffler is designed using the principles of our invention, the exit gases will have characteristics well within the limits allowed by the applicable governmental regulations.

The'perforated conduits with the spiral baffles to-' gether with the perforated chambers, which successive conduits and chambers are connected in series alignment, progressively absorb and dissipate the sound waves, heat and the velocity of the exhaust gases so that the final product issuing from the muffler is to acceptable standards. I The series alignment of the two or more conduit and chamber units dissipate and diffuse the high velocity, hot gases and sound waves so that they may be converted to a relatively moderate temperature and low sound level. The progressive suppression and absorption of the sound waves reduces the resonance and velocity of the gases by means of the series connected conduit and chamber units and by means of sound and heat retarding effect of the attenuation or insulation material. The tightly packed attenuation or insulation material will have numerous inner communicating chambers to trap and dampen the sound waves and to cool the exhaust gases. Each perforation or aperture in the conduits and chambers acts as an orifice of a venturi so that as the high velocity gases pass therethrough, they produce a venturi effect which contributes to the LII dispersion of the hot gases and of the high energy noise source. As soon as the engine has been cut off, the exhaust gases within the conduit and chamber units are dissipated by a normal pressure equalization process.

We claim:

1. In a muffler having a housing with an inlet and an outlet, a first chamber in said housing having perforations in the walls thereof, a conduit in said housing connecting said inlet with said chamber and having perforations in the wall thereof, baffle means in said conduit for diverting exhaust gases out through the perforations in said conduit, another chamber in said housing having perforations in the walls thereof and being operatively connected with the outlet in said housing, another conduit in said housing operatively connecting said another chamber with said first chamber, baffle means in said another conduit for diverting exhaust gases out through the perforations in said conduit, and insulating material surrounding said chambers and conduits within said housing, whereby said exhaust gases pass from chamber-to-chamber as the undesirable characteristics are substantially dispersed and dissipated into said insulating material prior to discharge from said muffler.

2. In a muffler as claimed in claim 1 wherein three chambers are mounted in said housing and are interso as to force all gases to be diverted through the perforations in the walls of said conduits.

6. In a muffler for an engine having a housing with an inlet and an outletspaced from each other, at least two conduit and chamber units connected in series within said housing, attenuation material surrounding said units within said housing, at least one said conduit and chamber unit having a conduit extending from said inlet in the housing to within a chamber of said unit, said conduit having perforations in the walls thereof both inside and outside said chamber, baffle means carn'ed by each conduit for diverting exhaust gases through the perforations in the'walls of said conduit, said chamber having perforations formed through the walls thereof to permit communication from within said chamber to the attenuation material in said housing, at least one other one of said units having means connecting a chamber with said outlet, an inlet conduit of said last-named unit extending from within an immediately preceeding chamber of a conduit and chamber unit to within the chamber of said last-named unit, whereby sound waves and heat carried by exhaust gases part of said sound waves and heat pass through the perforations in the walls of the chambers and are dissi-,

pated by said attenuation material. I

9. The muffler asclaimed in claim 6 wherein the remote end of each conduit is closed so as to force the exhaust gases to pass through the perforations in the side walls of said conduit and into either the attenuation material or into the associated chamber of its conduit and chamber unit.

10. In a muffler for an internal combustion engine having a housing with an inlet and an outlet, at least two conduit and chamber units connected in series within said muffler, a conduit of the first of said units being connected to said inlet and extending to within a chamber of said unit, a second conduit and chamber unit having said outlet of said housing extending into a chamber of said second unit and having'a conduit ex tending from within a chamber of a preceeding conduit and chamberunit to within said chamber of said second conduit and chamber unit, attenuating and insulating material surrounding said units within said housing, each conduit and chamber unit having perforations formed through the walls thereof, spiral baffle means mounted in each conduit for diverting exhaust gases into a spiral pathand through the perforations in the walls of said conduit and into the chamber of its associated conduit and chamber unit, the interior of each chamber communicating withthe attenuating and insulating material in said housing through the perforations in said chamber whereby sound waves and heat carried by exhaust gases are dispersed and dissipated partially into said attenuating and insulating material and partially through successive conduit and chamber units in series arrangement until said gases discharged from the outlet at a substantially reduced sound and heat level.

11. A muffler for an engine having a housing with an inlet and an outlet, plural sound and heat dissipating means connected in series within said housing, attenuation material surrounding said plural means within said housing, each of said means having a chamber and an inlet conduit with said inlet conduit extending into said chamber, the inlet conduit of the first of said means being connected to the inlet in said housing and the chamber of the last of said means being connected to the outlet in said housing, the inlet conduit of each successive one of said means having perforations through the walls thereof and being connected'to the chamber of the immediately preceeding means, each chamber of said means having perforations formed through the walls thereof to permit communication. from within said chamber to the attenuation material in said housing, whereby sound waves and heat carried by exhaust gases are dispersed and dissipated through the successive means and into said attenuation material until said gases are discharged from the outlet at a substantially rations in the walls of said conduit. 

1. In a muffler having a housing with an inlet and an outlet, a first chamber in said housing having perforations in the walls thereof, a conduit in said housing connecting said inlet with said chamber and having perforations in the wall thereof, baffle means in said conduit for diverting exhaust gases out through the perforations in said conduit, another chamber in said housing having perforations in the walls thereof and being operatively connected with the outlet in said housing, another conduit in said housing operatively connecting said another chamber with said first chamber, baffle means in said another conduit for diverting exhaust gases out through the perforations in said conduit, and insulating material surrounding said chambers and conduits within said housing, whereby said exhaust gases pass from chamber-to-chamber as the undesirable characteristics are substantially dispersed and dissipated into said insulating material prior to discharge from said muffler.
 2. In a muffler as claimed in claim 1 wherein three chambers are mounted in said housing and are interconnected by two conduits.
 3. In a muffler as claimed iN claim 1 wherein said baffles in said conduits are spiral-shaped baffles for diverting said gases into a spiral-shaped path.
 4. In a muffler as claimed in claim 1 wherein said conduits extend into and are supported in their associated chambers, and wherein the walls of said conduits are perforated both inside and outside said associated chambers.
 5. In a muffler as claimed in claim 4 wherein the remote ends of said conduits in said chambers are closed so as to force all gases to be diverted through the perforations in the walls of said conduits.
 6. In a muffler for an engine having a housing with an inlet and an outlet spaced from each other, at least two conduit and chamber units connected in series within said housing, attenuation material surrounding said units within said housing, at least one said conduit and chamber unit having a conduit extending from said inlet in the housing to within a chamber of said unit, said conduit having perforations in the walls thereof both inside and outside said chamber, baffle means carried by each conduit for diverting exhaust gases through the perforations in the walls of said conduit, said chamber having perforations formed through the walls thereof to permit communication from within said chamber to the attenuation material in said housing, at least one other one of said units having means connecting a chamber with said outlet, an inlet conduit of said last-named unit extending from within an immediately preceeding chamber of a conduit and chamber unit to within the chamber of said last-named unit, whereby sound waves and heat carried by exhaust gases are dispersed and dissipated through successive conduit and chamber units in series arrangement until said gases are discharged from the outlet in a quieter and cooler condition.
 7. In a muffler as claimed in claim 6 wherein said baffle means in said conduits are spiral-shaped baffles for diverting the gases along a spiral-shaped path.
 8. The muffler as claimed in claim 6 wherein three conduit and chamber units are mounted in the series arrangement with the sound waves and heat of the gases passing successively from one unit to the next as part of said sound waves and heat pass through the perforations in the walls of the chambers and are dissipated by said attenuation material.
 9. The muffler as claimed in claim 6 wherein the remote end of each conduit is closed so as to force the exhaust gases to pass through the perforations in the side walls of said conduit and into either the attenuation material or into the associated chamber of its conduit and chamber unit.
 10. In a muffler for an internal combustion engine having a housing with an inlet and an outlet, at least two conduit and chamber units connected in series within said muffler, a conduit of the first of said units being connected to said inlet and extending to within a chamber of said unit, a second conduit and chamber unit having said outlet of said housing extending into a chamber of said second unit and having a conduit extending from within a chamber of a preceeding conduit and chamber unit to within said chamber of said second conduit and chamber unit, attenuating and insulating material surrounding said units within said housing, each conduit and chamber unit having perforations formed through the walls thereof, spiral baffle means mounted in each conduit for diverting exhaust gases into a spiral path and through the perforations in the walls of said conduit and into the chamber of its associated conduit and chamber unit, the interior of each chamber communicating with the attenuating and insulating material in said housing through the perforations in said chamber whereby sound waves and heat carried by exhaust gases are dispersed and dissipated partially into said attenuating and insulating material and partially through successive conduit and chamber units in series arrangement until said gases discharged from the outlet at a substantially reduced sound and heat level.
 11. A muffler for An engine having a housing with an inlet and an outlet, plural sound and heat dissipating means connected in series within said housing, attenuation material surrounding said plural means within said housing, each of said means having a chamber and an inlet conduit with said inlet conduit extending into said chamber, the inlet conduit of the first of said means being connected to the inlet in said housing and the chamber of the last of said means being connected to the outlet in said housing, the inlet conduit of each successive one of said means having perforations through the walls thereof and being connected to the chamber of the immediately preceeding means, each chamber of said means having perforations formed through the walls thereof to permit communication from within said chamber to the attenuation material in said housing, whereby sound waves and heat carried by exhaust gases are dispersed and dissipated through the successive means and into said attenuation material until said gases are discharged from the outlet at a substantially reduced level of sound and heat.
 12. In a muffler as claimed in claim 11 wherein spiral baffle means are mounted in each conduit for diverting exhaust gases into a spiral path and through the perforations in the walls of said conduit. 